Process of manufacturing oxygen.



V H. L. DOHERTY. PROCESS OF MANUFACTURING OXYGEN.

APPLICATION FILED MAY 15, 1911.

1,048,812. Patented Dec.31, 1912.

MW 8 5 61mm, Z1441 HENRY L. DOHERTY, OF NEW YORK, N. Y.

PROCESS OF MANUFACTURING OXYGEN.

Specification of Letters Patent.

Patented Dec. 31, 1912.

Application filed May 15, 1811. Serial No. 627,181.

To all whom it may concern:

Be it known that I, HENRY L. Domzn'rr, a citizen of the United States,and a resident of New York city, in the county of New York and State ofNew York, have invented certain new and useful Improvements in Processesof Manufacturing Oxygen, of which the following is a specification.

This invention relates to processes of manufacturing oxygen and, inparticular, to that class of such processes in which the oxygen isproduced by alternately forming barium peroxid by oxidizing barium OXldby atmospheric alr and decomposlng the eroxid'to liberate the extra atomof oxygen iield by the molecule of peroxid.

The object of this invention is to improve present methods of oxygenmanufacture 1n such a way as to diminish the expenditure of fuel on theone hand and to increase the volume of oxygen roduced in a given timefrom a given weig t of barium peroxid on the other.

To this end my invention consists, briefly stated, in carrying out theoperations of peroxidizing and deoxidizing the barium oxid oncomparatively lar e masses of the material contained in suita le towershaving a thick non-conducting lining, the roper temperature of the oxidbeing maintained b bypassing a part of the oxygen drawn 0 dur- 1n thede-oxidizing operation back to the OXld towers through a superheater inwhich it is highly superheated, as well as other features whichwill bemore fully described later.

In the accompanying drawings I have illustrated diagrammatically anarrangement of apparatus suitable for carrying out my invention. In thisI have indicated the course of the gaseous currents during one base ofthe operation, the air current being indicated by the oxygen current byO and the waste air current by N-- The method of operation is asfollows: The air which is to be used in peroxidizing the barium oxid isforced by the blowing engine 1 to the first purifying tower 2. This isfilled with some material capable of absorbing water and carbonic acidsuch as lime (CaO), or a mixture of lime and calcium chlorid. In thistower the major parts of the moisture and carbonic acid are absorbed andthe air next passes to other purifying apparatus where the last tracesof water and carbonic acid are removed. I

prefer to use anhydrous sulfuric acid and caustic soda or potash for thefinal purification but any other satisfactor method may be substituted.The anhy rous sulfuric acid contained in chamber 3, while the caustlcalkali is contained in chamber moisture and carbonic acid, passes tothe' heat interchangers 21, 22 and 5 throu h the pipe 18 and connections19 and '20, s own. A valve, 18', on 18 serves to regulate thedistribution of air between 21 and 22. In 21 and 22 the air is subjectedto a preliminary heating to approximately 1000 F. by the sensible heatof the nitrogen residue from the peroxidizing operation and of thepartially cooled oxygen from the heater 5. The heat interchangers 21, 22and 5 may be of any suitable construction of the double-surfacerecuperator type. From 21 and 22 the partially heated air passes throughthe connections 23, 24 and 25 to the final heat interchanger 5. In 5,which, like 21 and 22, may be of any suitable surface recuperatcrconstruction, the entering air is further heated by the sensible heat ofthe oxygen which is, at the same time, being drawn oil from an oxidvessel which is undergoing de-oxidation. The air should leave thechamber 5 at a temperature approximating 1200 F. and should not be below1100 F. With the air at this temperature the heat developed in theperoxidizing of the barium oxid is sufficient to maintain the oxid atthe proper temperature. From 5 the heated and purified air passesthrough the pipes 7 or 8 to one of the barium oxid towers 9 or 10.Valves 7' and 8 on 7 and 8 respectively serve to control the flow of theair. With the setting of the valves assumed in the diagram the directionof flow of the currents is shown by the arrows. The valve 7' being openand 8 closed, the air flows through 7 to the bottom of tower 9, passesup through 9 in contact with the barium oxid with which 9 is filled, thenitrogen and any unabsorbed oxygen discharging through the pipe 11,which is provided with a valve 11', and pipe 26 to the heat interchanger21, after passing through which it discharges through the pipe 27. Theoxid in the tower 9 is maintained at a temperature of about 1200 F. inthe manner described later. At this temperature the barium oxid takes upan additional atom of oxygen to form peroxid according to the reaction,

BaO-tO BaO In carrying out this method of oxygen manufacture it is notfound practicable to convert the whole of the BaO to BaO owing to thedifticulty and slowness of carrying the reaction to completion.Therefore, I continue the peroxidizing operation only so long as theabsorption of the oxygen proceeds readily and the escaping gas from 11contains very little oxygen. The exact time required for this operationdepends mainly upon the temperature and the rate at. which air issupplied to 9. \Vith a properly designed plant, the duration of eachperoxidizing operation will be from five to fifteen minutes. The precisemanner of handling the per-oxidizing operation may, however, be variedwithin wide limits, and I therefore do not limit myself to the specificdetails of the same outlined.

While the material in 9 has been undergoing peroxidation in the manneroutlined, the charge of BaO in 10 has been undergoing de-oxidation andheating in the manner described below.

The charge in 10, having been previously subjected to peroxidation,consists in part of barlum peroxid (13:10,). The peroxidized barium ischiefly on the outer shell of the fragments of BaO. During thede-oxidation the tower 10 is connected through the pipe 13, oxygenpassages of heater 5, pipe 6, oxygen passages of heat interchanger 22and pipe 17 with the exhauster 44, which is operated to produce a highvacuum in 10. Under this vacuum the BaO previously formed in 10 givesoff the extra atom of oxygen thus,

The temperature in 10 being maintained at a relatively high point (about1300) in the manner described below, the liberated oxygen enters theheater 5 at about this temperature. The air entering 5 at a temperatureof about 1000 or below takes up additional heat from the oxygen andthereby has its temperature considerably increased. The oxygen leaves 5at about 1000 and passes through (3 to the heat interchanger 22. Here itis still further cooled by a portion of the air which is regulated involume by the valve 18. Leaving 22 at a temperature of about 100 or sothe oxygen may be passed directly to the exhauster 4s or passed througha condenser where it may be cooled by water to increase the capacity ofthe exhauster. From 44 exhauster the oxygen passes through the pipe 28to the storage tank or gas holder 29. From 23, or from 29 if preferred,a portion of the oxygen is drawn olt' through the pipe 32- to the superheater 33. Here it is highly heated (to from 1800 to 2000 F.) and passesthence to one of the o-xid towers 9 or 10. As indicated in the diagramthe hot oxygen from 33 is passing through the pipe 31 to tower 10. Hereit parts with its superheat; to the oxid in 10, which is being cooled bythe deoxidizing reaction mentioned, and by the unavoidable loss of heatinthe oxygen drawn otf, as well as by a small loss'of heat to theatmosphere by ra- (liation and conduction from the wall of the chamber.This last. loss may be reduced to a minimum by making the walls doubleso as to leave an air space and then connecting this space with the pipeleading to the exhauster, as well as by jacket-ing the outer wall. Thesuperheater 33 is preferably heated by producer gas generated in a gasproducer, 30, and conducted to 33 by the conduit 37. Air is supplied toproducer 36 by the blower 38 through pipe 39. A branch, 40, of 30diverts the larger portion of the air to the superheater 33 to burn theproducer gas. If preferred, the combustion in 33 may be conducted undernatural draft instead of forced draft. The products of the combustionescape through the stack 41. The bypassed oxygen of course mingles withthe oxygen given off from the barium oxid and again passes through thesystem to the holder 29.

W hen the gas discharging from 9 shows a considerable percentage ofoxygen, indicat ing that the oxidizing reaction in '9 is diminishing invelocity and that a considerable quantity of oxygen is escapingflbSUIPtllOIl by the oxid, the valves are shifted so that the air flowsto the chamber 10 while the exhauster lLCllaWS from the chamber 9. Toaccomplish this in the apparatus diagrammed valves 7', 11, 13 and 34"are closed and S, 15, 35 and 42 opened. Air is now passing through 8 to10, where its oxygen is abstracted, the residual nitrogen pa singthrough 43, 26, 21 and 27 to the atm sphere or to storage when utilized.Chamber 9 is connected in its turn to the exhauster 4 1 through 15, 5,6, 22 and 17. Oxygen is by-passing back from 28 through 32, 33 and 35 to9.

l/Vhen the valves are changed the air valves are first shifted, thetower 10 being preferably left on the exhauster until the entering airhas displaced practically all the oxygen left in the chamber. Owing tothe high comparatively vacuum maintained in 10 during deoxidation,however, the quantity of free oxygen in 10 at any time is not very largeand the displacement of it before shifting the valves on the oxygenlines may be dispensed with if preferred. When a sufficient time haselapsed for the disroman glacementof the oxygen (which interval isetermined by experiment on starting operations) the oxygen valves areshifted so that tributed in about the same relative proportion as thetwo gases nitrogen and oxygen occur in the atmosphere. In this way, in

, in 5 to impart a final heating connection with the use of the oxygenalone to the air, I secure a perfectly balanced in the heatinterchangers, since the heat capacities of the'two currents areapproximately equalized.

-In the resent used methods of maln'ng oxygen f i'om barium oxid(commonly known as Brins process) the oxid is heated in small retorts byan external flame. Since barium oxid is a fairly good non-conductor ofheat this method of heating is far from eflicient. Besides, radiationlosses are heavy owing to the comparatively large extent of surface ofthe containers relative to the quantity of BaO. The heating of thebarium oxid is far from uniform, the temperature of the oxid lying nextto the wall of the retorts being-considerably. higher than the interiorof the charge. 1

By my improved method of carrying out the operation, I make it possible,1st, to secure a practically perfect heat recuperation;

2nd, by internal heating of the charge, I

reduce the heat losses from the barium chambers to a negligible quantityby making it possible to use practically perfect heat insulating deviceson the exterior surfaces of the shells of the chambers and to operateupon large masses of the BaO at one time whereby the rate of yield ofthe oxygen is greatly increased.

It is to be understood that I do not limit I myself in any way in regardto the temperatures and pressures employed in the BaO towers. I maystate, however, that I find it advantageous during oxidation of the BaOto finish u i the operation at a pressure of about 25 1 s. per sq. in.absolute and during deoxidation to finish up the operation atapproximately 2 lbs. absolute.

It isalso to be understood, that I do not limit myself to the use of myprocess in connection with the manufacture of oxygen specifically, butthat I claim it in connection with any similar gas producing process.

Having described my invention, what I claim is 1. In the manufacture ofoxygen from a peroxid the method of heating the peroxid which comprisesre-heating a portion of the oxygen evolved from the said peroxid andcontacting the said re-heated oxygen with the said peroxid.

2. In the manufacture of oxygen from a peroxid the method of heating theperoxid eat transfer which comprises re-heating 'a portion of the oxygenevolved from. the said peroxid and contacting the said re-heated oxygenwith the said peroxid the volume of thereheated oxygen r ative to thetotal volume of the oxygen evolved being such as will carry suflicientheat above the temperature oxid to ap roximately balance the loss ofheat from t e said peroxid due to the evolution of its oxygen.

3. In the manufacture of oxy from a peroxld the method of heatingperoxid F which comprises re-heating a ortion of the ioxygen evolvedfrom the sai peroxid and ,contacting the said re-heated oxygen with thesaid peroxid, the temperature to which :the re-heated oxygen is raisedbeing such a as will impart to the said re-heatcd oxygen a quantity ofavailable heat suflicient to approximately balance the loss of heat fromthe said peroxid due to evolution of its oxygen.

4. In the manufacture of oxygen from a peroxid, the method of heatingthe peroxid which comprises re-heating a ortion of theoxygen evolvedfrom the sai peroxid and contacting the'said re-heated oxygen with thesaid peroxid, the volume of the re-heated oxygen relative to thevolumeof the oxygen evolved from said peroxid, and the temis raised,being such as will impart to the able heat sufiicient to approximatelybalance the loss of heat from the said peroxid, due to evolution of itsoxy en.

peroxidized metallic oxid, the method of heating the said oxid whichcomprises the continuous withdrawal of a portion of theevolved oxygen,the re-heating of the said portion of oxy n, and the continuousbypassing. of sai re-heated portion back to the said metallic oxid.

6. In the manufacture of oxygen from a peroxidized metallic oxid, themethod of heating the said oxid which comprises the continuouswithdrawal of a portion of the evolved oxygen, the reheating of the saidportion of oxygen, the-continuous by-passing of the saidre-heatedportion'of oxygen back to the said metallic" oxid, and thepassing of thesaid said oxid, where y the available heat of the saidre-heated portion is transferred to said oxid, the volume of the portionof oxygen so withdrawn and the temperature to which it is re-heatedbeing so re latedthat the available heat imparted to t c said re-heatedportion of 0 en will ap roximately balance the loss 0 eat from t c saidoxid due to evolution of oxygen from the same.

7. In the manufacture of oxygen from peroxidized barium oxid, the methodof heatperature to which the said re-heated oxygen 5. In the manufacture0 oxygen from a portion in contact with the.

at which it isdesired to maintain the persaid re-heated oxygen aquantity of avail- 7 ing the said barium oxid, which comprises thecontinuouslwit-hdrawal of a portion of the oxygen evolved from saidperoxidized barium oxid during the partial'deoxidation of the same, there-heating of the said portion of oxygen, and the continuous by-passingof said re-heated portion back into contact with the peroxidized bariumoxid wh1le the same is undergoing partial deoxidation, whereby the saidoxid is maintained at a reactive temperature.

8. In the manufacture of oxygen from peroxidized barium oxid, the methodof heating the said oxid, which comprises the continuous withdrawal of aportion of the oxygen evolved from said peroxidized barium oxid duringthe deoxidation of the same, the re-heating of the said portion ofoxygen, and the continuous return to and contacting with the said oxidof the said re-heated portion, whereby the available heat of saidreheated portion of oxygen is transferred to said oxid, the volume ofthe portion of oxygen so withdrawn and the temperature to which it isre-heated being so regulated that the available heat imparted to thesaid reheated portion of oxygen will approximately balance the loss ofheat from the said oxid due to evolution of oxygen from the same.

9. The process of manufacturing oxygen, which comprises peroxidizing ametallic oxid by passing air in contact with the same at a suitabletemperature and under a suitable pressure, reducing the pressure uponthe peroxidized metallic oxid until the same evolves oxygen,continuously withdrawing the evolved oxygen from the said oxid,reheating a portion of the said oxygen and returning the re-heatedportion in contact with the said oxid to maintain the temperature of thesame.

10. The process of manufacturing oxygen, which comprises peroxidizing ametallic oxid by passing air in contact with the same at a suitabletemperature and pressure, reducing the pressure upon the peroxidizedmetallic oxid until the same evolves oxygen, continuously withdrawingthe evolved oxygen from the oxid, re-heating a portion of the saidoxygen and returning the re-heated portion in contact with the said oxidto heat the same, the volume of said re-heated portion of oxygenrelative to the evolved oxygen and the temperature to which the saidoxygen is re-heated being so regulated that the available heat impartedto the said re-heated oxygen will approximately balance the loss of heatfro-m the said metallic oxid due to the evolutionof the oxygen from thesame.

11. The process of manufacturing oxygen, which comprises peroxidizing ametallic oxid by passing air in contact with the same at a red heat andat a pressure above that of the atmosphere, reducing the pressure uponthe peroxidized metallic oxid until the same evolves oxygen,continuously withdrawing the evolved oxygen from the oxid, re-heating aportion of the said oxygen and returning the re-heated portion incontact with the said oxid to heat the same, the volume of said rcheatedportion of oxygen relative to the evolved oxygen and the temperature towhich the said oxygen is re-heated being so regulated that the availableheat imparted to the said re-heated oxygen will approximately balancethe loss of heat from the said metallic oxid due to the evolution of theoxygen from the same.

12. The process of manufacturing oxygen, which comprises peroxidizing ametallic oxid by passing air in contact with the same at a red'heat andat a pressure of approximately 15 lb. per sq. in. above that of theatmosphere, reducing the pressure upon the peroxidized metallic oxiduntil the same evolves oxygen, continuously withdrawing the evolvedoxygen from the oxid, re-heating a portion of the said oxygen andreturning the reheated portion into contact with the said oxid to heatthe same while it is undergoing deoxidation, the volume of the saidre-heated portion of oxygen relative to the evolved oxygen and thetemperature to which the same is re-heated being so regulated that theavailable heat imparted to the said re-heatcd oxygen will approximatelybalance the loss of heat from the'said' metallic oxid during theevolution of the oxygen from the same.

13. The process of manufacturing oxygen, which comprises peroxidizing ametallic oxid by passing air in contact with the same at a temperatureof approximately 1250 to 1300 degrees Fah. and a pressure ofapproximately 15-lb. per sq. in. above that of the atmosphere, reducingthe pressure upon the peroxidized metallic oxid to at or below 2 lb.absolute, whereby the peroxid previously formed is more or lessdissociated with the evolution of oxygen, withdrawing the evolved oxygenfrom contact with the said oxid, re-heating a portion of the said oxygenand returning the re-heated portion into contact with the said oxid toheat the same while it is undergoing deoxidation, the volume of the saidre-heated portion relative to the total volume of oxygen evolved and thetemperature to which the said portion is heated being so regulated thatthe available heat imparted to the said re-heated oxygen willapproximately balance the loss of heat from the said metallic oxid whilethe same is undergoing deoxidation.

14. The process of manufacturing oxygen, which comprises peroxidizingbarium oxid by passing air in contact with the same at a suitabletemperature and pressure reducing the pressure upon the peroxidizedbarium oxid until the same evolves oxygen, continuously withdrawing theevolved oxygen from the said oxid, re-heating a portion of the saidoxygen, and returning the reheated portion in contact with the said oxidto maintain the temperature of the same.

15. The process of manufacturing oxygen, which comprises peroxidizingbarium oxid by passing air in contact with the same at a suitabletemperature and pressure, reducing the pressure upon the peroxidizedbarium oxid until the same evolves oxygen, continuouslywithdrawing theevolved oxygen from the oxid, re-heating a portion of the said oxygenand returning the re-heated portion in contact with the said oxid toheat the same, the volume of said re-heated portion of the oxygenrelative to the total evolved oxygen and the temperature to which thesaid portion is heated being so regulated that the available heatimparted to the said re-heated oxygen will approximately balance theloss of heat from the said metallic oxid during the evolution of oxygenfrom the same.

16. The process of manufacturing oxygen, which comprises peroxidizingbarlum oxid by passing air in contact with the same at a red heat and atapressure above that of the atmosphere, reducing the pressure upon theperoxidized barium oxid until the same evolves oxygen, continuouslywithdrawing the evolved oxygen from the oxid, re-heating a portion ofthe said .oxygen and returning the re-heated portion into contact withthe said barium oxid to heat the same, the volume of said re-heatedportion of oxygen relative to the evolved oxygen and the temperature towhich the same is re-heated being so regulated that the available heatimparted to the said re-heated ox gen will approximately balance theloss of heat from the said metallic oxid during the evolution of oxygenfrom the same.

17. The process of manufacturing oxygen, which comprises peroxidizingbarium oxid by passing air in contact with the same at a red heat and ata pressure of approximately 15 lb. per sq. 1n. above that of theatmosphere, reducing the pressure upon the peroxidized barium oxid untilthe same evolves oxygen, continuously withdrawing the evolved oxygenfrom the oxid, re-heating a portion of the said oxygen and returning there-heated portion into contact with the said oxid to heat the same whileit is undergoing deoxidation, the volume of the said re-heated portionof oxygen relative to the evolved oxygen and the temperature to whichthe same is re-heat'ed being so regulated that the available heatimparted to the said re-heated oxygen will approximately balance theloss of heat from the said barium oxid during the evolution of oxygenfrom the same. I

18. The process of heating gas-evolving material to cause evolution ofgas, which comprises reheating more or less of the gas evolved from saidmaterial, and assing the said reheated gas in contact wit said materialat a pressure below atmospheric pressure to cause evolution of gas fromsaid material.

19. The process of heating gas-evolvin material to cause evolution ofgas, whic comprises withdrawing a portion of the gas evolved from saidmaterial, reheating said portion of evolved gas to a temperature abovethe average temperature at which it is desired to maintain saidmaterial, and passing said reheated gas in contact with said material ata pressure below atmospheric pressure to heat the same.

Signed at New York city, in the county of New York and State of New Yorkthis 13th day of May, A. D. 1911.

HENRY L. DOHERTY.

Witnesses:

FRANK L. BLACKBURN, S. B. SEVERBON.

